Demonstrates client-side raster reprojection between various projections.
This example shows client-side raster reprojection between various projections.
import Map from 'ol/Map.js';
import TileGrid from 'ol/tilegrid/TileGrid.js';
import TileLayer from 'ol/layer/WebGLTile.js';
import View from 'ol/View.js';
import WMTS, {optionsFromCapabilities} from 'ol/source/WMTS.js';
import WMTSCapabilities from 'ol/format/WMTSCapabilities.js';
import proj4 from 'proj4';
import {OSM, TileImage, TileWMS} from 'ol/source.js';
import {createXYZ} from 'ol/tilegrid.js';
import {getCenter, getWidth} from 'ol/extent.js';
import {get as getProjection, transformExtent} from 'ol/proj.js';
import {register} from 'ol/proj/proj4.js';
proj4.defs(
'EPSG:27700',
'+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 ' +
'+x_0=400000 +y_0=-100000 +ellps=airy ' +
'+towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 ' +
'+units=m +no_defs',
);
proj4.defs(
'EPSG:23032',
'+proj=utm +zone=32 +ellps=intl ' +
'+towgs84=-87,-98,-121,0,0,0,0 +units=m +no_defs',
);
proj4.defs(
'EPSG:5479',
'+proj=lcc +lat_1=-76.66666666666667 +lat_2=' +
'-79.33333333333333 +lat_0=-78 +lon_0=163 +x_0=7000000 +y_0=5000000 ' +
'+ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs',
);
proj4.defs(
'EPSG:21781',
'+proj=somerc +lat_0=46.95240555555556 ' +
'+lon_0=7.439583333333333 +k_0=1 +x_0=600000 +y_0=200000 +ellps=bessel ' +
'+towgs84=674.4,15.1,405.3,0,0,0,0 +units=m +no_defs',
);
proj4.defs(
'EPSG:3413',
'+proj=stere +lat_0=90 +lat_ts=70 +lon_0=-45 +k=1 ' +
'+x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs',
);
proj4.defs(
'EPSG:2163',
'+proj=laea +lat_0=45 +lon_0=-100 +x_0=0 +y_0=0 ' +
'+a=6370997 +b=6370997 +units=m +no_defs',
);
proj4.defs(
'ESRI:54009',
'+proj=moll +lon_0=0 +x_0=0 +y_0=0 +datum=WGS84 ' + '+units=m +no_defs',
);
register(proj4);
const proj27700 = getProjection('EPSG:27700');
proj27700.setExtent([-650000, -150000, 1350000, 1450000]);
const proj23032 = getProjection('EPSG:23032');
proj23032.setExtent([-1206118.71, 4021309.92, 1295389.0, 8051813.28]);
const proj5479 = getProjection('EPSG:5479');
proj5479.setExtent([6825737.53, 4189159.8, 9633741.96, 5782472.71]);
const proj21781 = getProjection('EPSG:21781');
proj21781.setExtent([485071.54, 75346.36, 828515.78, 299941.84]);
const proj3413 = getProjection('EPSG:3413');
proj3413.setExtent([-4194304, -4194304, 4194304, 4194304]);
const proj2163 = getProjection('EPSG:2163');
proj2163.setExtent([-8040784.5135, -2577524.921, 3668901.4484, 4785105.1096]);
const proj54009 = getProjection('ESRI:54009');
proj54009.setExtent([-18e6, -9e6, 18e6, 9e6]);
const layers = {};
layers['osm'] = new TileLayer({
source: new OSM(),
});
layers['wms4326'] = new TileLayer({
source: new TileWMS({
url: 'https://ahocevar.com/geoserver/gwc/service/wms',
crossOrigin: '',
params: {
'LAYERS': 'ne:NE1_HR_LC_SR_W_DR',
'TILED': true,
'VERSION': '1.1.1',
},
projection: 'EPSG:4326',
// Source tile grid (before reprojection)
tileGrid: createXYZ({
extent: [-180, -90, 180, 90],
maxResolution: 360 / 512,
maxZoom: 10,
}),
// Accept a reprojection error of 2 pixels
reprojectionErrorThreshold: 2,
}),
});
layers['wms21781'] = new TileLayer({
source: new TileWMS({
attributions:
'© <a href="https://shop.swisstopo.admin.ch/en/products/maps/national/lk1000"' +
'target="_blank">Pixelmap 1:1000000 / geo.admin.ch</a>',
crossOrigin: 'anonymous',
params: {
'LAYERS': 'ch.swisstopo.pixelkarte-farbe-pk1000.noscale',
'FORMAT': 'image/jpeg',
},
url: 'https://wms.geo.admin.ch/',
projection: 'EPSG:21781',
}),
});
const parser = new WMTSCapabilities();
layers['wmts3413'] = new TileLayer();
const urlA =
'https://map1.vis.earthdata.nasa.gov/wmts-arctic/' +
'wmts.cgi?SERVICE=WMTS&request=GetCapabilities';
fetch(urlA)
.then(function (response) {
return response.text();
})
.then(function (text) {
const result = parser.read(text);
const options = optionsFromCapabilities(result, {
layer: 'OSM_Land_Mask',
matrixSet: 'EPSG3413_250m',
});
options.crossOrigin = '';
options.projection = 'EPSG:3413';
options.wrapX = false;
layers['wmts3413'].setSource(new WMTS(options));
});
layers['bng'] = new TileLayer();
const urlB =
'https://tiles.arcgis.com/tiles/qHLhLQrcvEnxjtPr/arcgis/rest/services/OS_Open_Raster/MapServer/WMTS';
fetch(urlB)
.then(function (response) {
return response.text();
})
.then(function (text) {
const result = parser.read(text);
const options = optionsFromCapabilities(result, {
layer: 'OS_Open_Raster',
});
options.attributions =
'Contains OS data © Crown Copyright and database right ' +
new Date().getFullYear();
options.crossOrigin = '';
options.projection = 'EPSG:27700';
options.wrapX = false;
layers['bng'].setSource(new WMTS(options));
});
const startResolution = getWidth(getProjection('EPSG:3857').getExtent()) / 256;
const resolutions = new Array(22);
for (let i = 0, ii = resolutions.length; i < ii; ++i) {
resolutions[i] = startResolution / Math.pow(2, i);
}
layers['states'] = new TileLayer({
source: new TileWMS({
url: 'https://ahocevar.com/geoserver/wms',
crossOrigin: '',
params: {'LAYERS': 'topp:states'},
serverType: 'geoserver',
tileGrid: new TileGrid({
extent: [-13884991, 2870341, -7455066, 6338219],
resolutions: resolutions,
tileSize: [512, 256],
}),
projection: 'EPSG:3857',
}),
});
const map = new Map({
layers: [layers['osm'], layers['bng']],
target: 'map',
view: new View({
projection: 'EPSG:3857',
center: [0, 0],
zoom: 2,
}),
});
const baseLayerSelect = document.getElementById('base-layer');
const overlayLayerSelect = document.getElementById('overlay-layer');
const viewProjSelect = document.getElementById('view-projection');
const renderEdgesCheckbox = document.getElementById('render-edges');
let renderEdges = false;
function updateViewProjection() {
const newProj = getProjection(viewProjSelect.value);
const newProjExtent = newProj.getExtent();
const newView = new View({
projection: newProj,
center: getCenter(newProjExtent || [0, 0, 0, 0]),
zoom: 0,
extent: newProjExtent || undefined,
});
map.setView(newView);
// Example how to prevent double occurrence of map by limiting layer extent
if (newProj.isGlobal()) {
layers['bng'].setExtent(
transformExtent(proj27700.getExtent(), proj27700, newProj, 2),
);
} else {
layers['bng'].setExtent(undefined);
}
}
/**
* Handle change event.
*/
viewProjSelect.onchange = function () {
updateViewProjection();
};
updateViewProjection();
const updateRenderEdgesOnLayer = function (layer) {
if (layer instanceof TileLayer) {
const source = layer.getSource();
if (source instanceof TileImage) {
source.setRenderReprojectionEdges(renderEdges);
}
}
};
/**
* Handle change event.
*/
baseLayerSelect.onchange = function () {
const layer = layers[baseLayerSelect.value];
if (layer) {
layer.setOpacity(1);
updateRenderEdgesOnLayer(layer);
map.getLayers().setAt(0, layer);
}
};
/**
* Handle change event.
*/
overlayLayerSelect.onchange = function () {
const layer = layers[overlayLayerSelect.value];
if (layer) {
layer.setOpacity(0.7);
updateRenderEdgesOnLayer(layer);
map.getLayers().setAt(1, layer);
}
};
/**
* Handle change event.
*/
renderEdgesCheckbox.onchange = function () {
renderEdges = renderEdgesCheckbox.checked;
map.getLayers().forEach(function (layer) {
updateRenderEdgesOnLayer(layer);
});
};
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Raster Reprojection</title>
<link rel="stylesheet" href="node_modules/ol/ol.css">
<style>
.map {
width: 100%;
height: 400px;
}
.reprojection-form {
display: grid;
grid-template-columns: max-content max-content;
grid-gap: 5px;
gap: 5px;
}
</style>
</head>
<body>
<div id="map" class="map"></div>
<form class="reprojection-form">
<label for="base-layer">Base map:</label>
<select id="base-layer">
<option value="osm">OSM (EPSG:3857)</option>
<option value="wms4326">WMS (EPSG:4326)</option>
</select>
<label for="overlay-layer">Overlay map:</label>
<select id="overlay-layer">
<option value="bng">British National Grid (EPSG:27700)</option>
<option value="wms21781">Swisstopo WMS (EPSG:21781)</option>
<option value="wmts3413">NASA Arctic WMTS (EPSG:3413)</option>
<option value="states">United States (EPSG:3857)</option>
</select>
<label for="view-projection">View projection:</label>
<select id="view-projection">
<option value="EPSG:3857">Spherical Mercator (EPSG:3857)</option>
<option value="EPSG:4326">WGS 84 (EPSG:4326)</option>
<option value="ESRI:54009">Mollweide (ESRI:54009)</option>
<option value="EPSG:27700">British National Grid (EPSG:27700)</option>
<option value="EPSG:23032">ED50 / UTM zone 32N (EPSG:23032)</option>
<option value="EPSG:2163">US National Atlas Equal Area (EPSG:2163)</option>
<option value="EPSG:3413">NSIDC Polar Stereographic North (EPSG:3413)</option>
<option value="EPSG:5479">RSRGD2000 / MSLC2000 (EPSG:5479)</option>
</select>
<label for="render-edges">Render reprojection edges:</label>
<span><input type="checkbox" id="render-edges" /></span>
</form>
<script type="module" src="main.js"></script>
</body>
</html>
{
"name": "reprojection",
"dependencies": {
"ol": "10.2.1",
"proj4": "2.12.1"
},
"devDependencies": {
"vite": "^3.2.3"
},
"scripts": {
"start": "vite",
"build": "vite build"
}
}